The invention relates to closed crankcase ventilation, CCV, filters for diesel engines.
Diesel engines have crankcase vents to relieve pressure buildup in the engine. A frequent cause of pressure buildup in the engine is from air leaking past the piston rings into the crankcase. The air that is vented out of the crankcase, also known as blow-by gas or crankcase gas, contains soot and oil mist particles. For many years, the blow-by gas along with the oil and soot was vented to atmosphere through a xe2x80x9croad tubexe2x80x9d to direct the flow to a desired area such as the ground, or away from specific engine parts. In recent years, metal mesh filters have been used to try and remove some of the larger oil droplets from the blow-by stream. These have had mixed results in the field. There have also been aftermarket products which remove oil mist and soot from engine blow-by gas. These products have been designed for industrial and stationary applications, and are usually too large and bulky for mobile applications.
Over the past few years, for appearance and environmental reasons, there has been motivation to eliminate the xe2x80x9croad tubexe2x80x9d type of design, and close the crankcase ventilation system. Closing the crankcase ventilation system means returning the blow-by gas back to the incoming combustion air stream to the engine, for example, at the air cleaner, turbocharger, intake manifold, or other engine intake. If a closed crankcase system is used, aerosol-sized droplets and soots, which for the most part are ignored in an open system, should be removed. This is desired in a closed system in order to avoid adverse effects on various engine components, especially the turbocharger and aftercooler. To do this, a degree of filtration beyond metal mesh is desired.
Packaging a closed crankcase ventilation system in a diesel engine compartment is a problem because of limited space. The closed crankcase ventilation, CCV, system requires routing hoses from the crankcase vent on the engine to the CCV housing, and from the CCV housing to either the dirty side of the air filter or to the turbo inlet of the diesel engine. Furthermore, a drain line needs to be run from the CCV housing back to the oil sump. A xe2x80x9cstand alonexe2x80x9d CCV system will have certain envelope requirements. For example, in a mid-range diesel engine, e.g. 150 to 300 horsepower, a projected envelope size would be a cylindrical housing of about four inches outer diameter and six to seven inches long plus room for connecting hoses, drain lines and valves. In mobile diesel engine applications, finding this amount of space in a convenient location is a problem.
The invention of commonly owned copending U.S. patent application Ser. No. 09/387,819, filed Sep. 1, 1999, provides a diesel engine crankcase ventilation filter addressing and solving the above-noted packaging and space problem, including the provision of a flat low profile crankcase ventilation filter, and enabling mounting of the flat low profile filter housing directly on the diesel engine valve cover in a horizontal orientation, with minimum space requirements and minimum plumbing requirements.
The present invention provides another solution to the noted packaging and space problem. The present invention provides a modular flat low profile crankcase ventilation filter and housing, and in preferred form enabling mounting in a vertical orientation. In a desirable aspect, the invention enables a modular housing construction provided by a pair of clamshell housing halves having a top opening closed by a modular filter element inserted downwardly thereinto and closing and completing the housing.